Arrangement and method for illuminating the lens of the human eye

ABSTRACT

The present invention is directed to an arrangement for generating a variable illumination and irradiation for diagnosis and therapy, particularly for the human eye ( 1 ), and to a method for the application thereof. The object to be illuminated can be an artificial object or biological tissue. The arrangement for carrying out the illumination/irradiation of a human eye ( 1 ) comprises an illumination unit ( 2, 3 ), an optical imaging system ( 4 ), an evaluating unit, a central control unit ( 6 ) and an output unit ( 7 ). The illumination unit ( 2, 3 ) generates an illumination which is variable with respect to time and/or space and which is adapted to the diagnostic results. The solution according to the invention is provided chiefly for post-operative fine adjustment of the refractive power of photosensitive plastics already implanted in the eye ( 1 ). The latter can be optical lenses as well as other optical elements which are placed in a specific manner in the cornea. However, application of the invention for achieving dermatological effects is also conceivable.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority of International Application No.PCT/EP03/00129, filed Jan. 9, 2003 and German Application No. 102 00718.7, filed Jan. 10, 2002, the complete disclosures of which are herebyincorporated by reference.

BACKGROUND OF THE INVENTION

a) Field of the Invention

The present invention is directed to an arrangement for generating avariable illumination and irradiation for diagnosis and therapy,particularly for the human eye, and to a method for the applicationthereof. The object illuminated by the variable illumination can be anartificial object or biological tissue. However, with respect to theeye, it is also possible to irradiate other parts of the eye besides thelens, such as the cornea, retina or fundus. In particular, the inventioncan be used for fine adjustment of photosensitive plastics introducedinto the eye (according to WO 00/41650 and WO 01/71411). With plasticsof this type, the irradiation excites polymerization processes thatresult in irreversible chemical changes in the substance. The index ofrefraction, geometric shape and/or transmission behavior for the visibleuseful radiation and the geometric shape of the plastic body can bechanged in a defined manner by these processes. In this way, it ispossible to improve defective vision.

b) Description of the Related Art

Patents WO 00/41650 and WO 01/71411 describe lenses, particularlyintraocular lenses (IOL) in which polymerization of a polymer matrixcontained in the lens is excited by irradiation and the index ofrefraction or the shape of the entire lens can be changed in this way.With implanted IOLs, the problem exists that in approximately 50% ofpatients an acceptable visual acuity can be achieved only throughadditional corrective measures such as eyeglasses or contact lenses.This is the result, in part, of errors in eye measurements, deviationsin the positioning of the IOL and/or is due to the healing process. Withthe described IOLs, a correction of the IOL which is already implantedis made possible through directed irradiation by adapting to the actualconditions through changes in the index of refraction, the transmissioncharacteristics or the optically active shape. The irradiation of theIOL for exciting the polymerization process is preferably effected bymeans of laser sources or lamps emitting a high UV component of thelight. For this purpose, an He/Cd laser or an Xe/Hg lamp is used as theirradiation source. Illumination structures which may possibly berequired are generally produced by means of mechanical diaphragms and/orfilters.

However, there are disadvantages to arrangements of the kind describedabove in that the supply of patterns is limited by fixed diaphragms,there is no possibility of intensity distribution within the diaphragmpatterns, and dynamic processes can be realized, at best, through manualswitching and, therefore, hardly at all. Moreover, the generatedillumination patterns can not be adapted to individual findings and arenot adaptive or suitable for online regulation.

199 43 735 A1 describes a method and a device for directed irradiationof an eye by means of light from the UV-A and/or visible near infraredwavelength range. The irradiation brings about irreversible chemicalchanges in the eye lens substance which result in a change in the indexof refraction and/or in the transmission characteristics for the visibleuseful radiation and which accordingly make it possible to improvedefective vision. Successful treatment requires that the distribution ofthe refractive power of the eye being treated is determined over themost closely-knit, fullest area possible. The refractive powerdistribution desired after treatment and the data for the irradiationthat are required for this purpose are determined from these values.Inevitably, however, the eyeball must usually be fixated for theduration of the treatment.

Patents WO 02/26121 and WO 02/31576 describe solutions for theirradiation of optical lenses or lens systems made from photosensitiveplastics (according to WO 00/41650 and WO 01/71411) which are alreadyimplanted in the eye as intraocular lenses. In this solution, theirradiation patterns in question are determined by a computer programbased on a wavefront analysis that is carried out beforehand. Inaddition to a diagnostic element for monitoring before, during and afterirradiation, a surgical microscope is provided for additional visualobservation. However, this solution has disadvantageous results in thatthere is only one fixating light for the patient. Experience has shownthat it is difficult for the patient to concentrate on a stationaryfixating light for the duration of treatment, so that movements of theeye can nevertheless occur.

DE 198 12 050 A1 describes a method and an arrangement for illuminationin an ophthalmic microscope. A large variety of light mark geometries isgenerated by means of optoelectronic components and projected on theanterior portion or on the fundus of the eye. This solution is used forgeneral examination of the eye. An arrangement for generating sectionimages in transparent media is provided in DE 101 55 464.8, which hasnot yet been published. An ophthalmological examination device whichenables a perimetric examination as well as a general eye examinationhas also not been published (DE 101 51 314.3). The solutions containedin both of these references likewise provide for the use ofoptoelectronic components for generating illumination marks andillumination patterns.

OBJECT AND SUMMARY OF THE INVENTION

It is the primary object of the present invention to develop a methodand an arrangement for illumination and irradiation of a human eye fortherapeutic purposes and for correcting the characteristics ofphotosensitive plastics already implanted in the eye. An optimizedvisual acuity is adjusted in the patient by means of this correction, sothat additional aids such as eyeglasses or contact lenses need not beworn.

According to the invention, this object is met by an arrangement for theillumination/irradiation of a human eye, particularly of photosensitive,optically active plastics implanted in the eye, comprising anillumination unit, an optical imaging system, an evaluating unit, acentral control unit and an output unit. The illumination unit generatesan illumination which is variable with respect to time and/or space.

The proposed technical solution substantially comprises the illuminationunit and an optical imaging system and can be used as an independentunit or as an accessory unit for different ophthalmological devices suchas slit lamps, fundus cameras, laser scanners and OPMI devices. Thisresults in a broad range of applications that is not limited only to thefield of ophthalmology. The irradiation unit can also be used as anaccessory unit for various dermatological irradiation devices in orderto bring about a specific effect through directed irradiation withvariable illumination.

The invention will be described in the following with reference toembodiment examples.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 shows a possible basic construction of the arrangement accordingto the invention with a DMD microdisplay;

FIG. 2 shows another possible basic construction of the arrangementaccording to the invention with a LCOS microdisplay; and

FIG. 3 shows possible illumination patterns with the associatedintensity distribution.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows the basic construction of the arrangement according to theinvention for generating an illumination which is variable with respectto time and/or space for diagnosis and therapy, particularly of thehuman eye 1.

The arrangement substantially comprises an illumination unit, an opticalimaging system 4, an evaluating unit, a central control unit 6 and anoutput unit 7. The illumination unit comprises an illumination source 2and an optoelectronic component 3. The illumination source 2 iscontrollable with respect to its intensity and duration and, for thispurpose, possesses additional means for controlling and monitoring theemitted light. A lamp or laser source which is controllable with respectto the spectral composition of the light bundle is used as illuminationsource 2. The control of the spectral composition can be carried out bymeans of a filter wheel (not shown). A DMD (digital micromirror device)microdisplay is used as optoelectronic component 3. In order to ensure auniform illumination, a light conducting fiber, a glass mixing rod, anintegrator rod, or a suitable condenser arrangement 10 is used fortransmitting the light beam from the illumination source to themicrodisplay. The provided optical imaging system 4 has an adjustablenumerical aperture and a variable back focus for sharp imaging of theillumination pattern in different planes of the object space. In thisway, different illumination patterns can be generated along the opticalaxis in different planes of the object, e.g., on the front surface ofthe lens or back surface of the lens, and geometric-spatial effects canaccordingly be produced. This possibility of imaging the illuminationpatterns in different planes can advantageously be combined with adistance control and/or a focusing aid for the eye. In this way, theposition along the optical axis can also be accurately adjusted andmaintained constant. The focusing aid can be carried out based on theprinciple of multiple spot imaging using a high aperture in which all ofthe individual spots coincide only in the target plane and result in oneindividual spot. A distance control can be carried out, for example, bymeans of known four-quadrant receivers which evaluate the vertexreflection of the cornea. The variably adjustable numerical aperture canbe used to regulate the intensity of the illumination pattern in theimaging plane on the one hand and, on the other hand, to maintain thecurrent limit values for the illumination in the eye by influencing thebeam density at the retina.

By combining the adjustable aperture diaphragm with the function of theadjustable back focus or focal length and the realization of dynamicillumination patterns, specific irradiation sequences with specialpatterns can be realized at determined locations with continuousmonitoring of the permissible radiation dose. Position control andposition correction are carried out by means of an eyetracker unit andensure an exact illumination only in the aligned focused state evenduring eye movements, so that mechanical fixation of the patient's eyecan be dispensed with.

Further, an observation system 5 and an evaluating unit are provided formeasurement, evaluation, documentation and readout. The evaluating unitcomprises an image-recording unit and a processing unit. The centralcontrol unit 6 for input, acquisition, processing and storage of datahas a user surface 9 and an interface 8. A monitor, a printer and/or aHMD (head mounted display), for example, are used as output unit 7 forvisualization and readout of data.

In contrast, FIG. 2 shows the basic construction of the arrangementaccording to the invention for generating structured illumination inwhich a LCOS (liquid crystal on silicon) reflecting microdisplay is usedas optoelectronic component 3 instead of a DMD microdisplay. However,transmissive LCD (liquid crystal display), self-luminous LED (lightemitting diode) or OLED (organic light emitting diode) optoelectroniccomponents 3 can also be used. In the basic construction shown in FIG.1, a microscanning mirror with two individually controllable oscillationplanes could also be used instead of the microdisplay.

In the method for generating illumination which is variable with respectto time and/or space particularly when operating one of the arrangementsdescribed above, after the findings or result data that were determinedbeforehand (refraction state) have been entered from the central controlunit 7, the parameters of the illumination radiation which are requiredfor the intended purpose are determined and conveyed to the illuminationsource 2 and the optoelectronic component 3. Based on the determineddata, static or dynamic irradiation patterns geared to the specificapplication can be generated for directed spatial and temporalsequences.

The method is suitable particularly for illumination/irradiation ofoptical lenses or other elements already implanted in the eye. Theseelements comprise photosensitive base materials according to Patents WO00/41650 and WO 01/71411 so that their optical-mechanicalcharacteristics can be changed within a certain time period bystimulation with light.

Apart from intraocular lenses (IOL), the plastic lenses to beilluminated can be, in particular, anterior chamber lenses (e.g.,Artisan lenses and Nuvita lenses) or intraocular contact lenses (ICL).

However, there are also other optical elements such as intercornealrings, as they are called, which can be placed in the cornea in aspecific manner and cause a change in the refractive conditions of thecornea due to their shape and position. Implantation is relativelyconservative for the patient because neither the epithelium nor theendothelium are damaged or altered except for a peripheral entry point(mounting opening). These intercorneal rings are placed in the cornea ina specific manner and, due to their shape and position, cause atightening of the surface of the cornea to varying extents andaccordingly change the refractive conditions of the cornea. Since themethod is not necessarily limited to the ring structure, differentlyshaped elements such as thin disks are also possible.

FIG. 3 shows possible irradiation patterns and the associated intensitydistributions. Result data may come from preliminary examinations withappropriate measuring instruments or can be determined within the deviceitself. In this connection, possible result data may include results ofa wavefront analysis and data from topography examinations. It is evenuseful and conceivable to combine the data from different examinations.The result data can be transferred by entering them manually through theuser surface 9 or, more conveniently, by transferring the data via theinterface 8. The irradiation pattern generated by the illuminationsource 2 and the optoelectronic component 3 is imaged in the objectspace by the imaging system 4 in a plane which is freely adjustablewithin certain limits. The observation system 5 is used for visuallymonitoring and observing the eye 1 during the irradiation process. Forpurposes of automated image evaluation and in order to enable onlinecontrol, the corresponding measured values are supplied to theevaluating unit by an image-recording and processing unit. Forrecording, processing, documentation and evaluation, the recorded imagesand data are further processed, logged and stored by the central controlunit 6. An output unit 7 documents the evaluation results.

The use of an eyetracker unit comprising a camera and an IR illuminationis particularly advantageous. The eyetracker unit can be coupled in,e.g., by a beam splitter, monitors possible eye movements and checkswhether or not the generated illumination patterns strike exactly theareas of the eye or of the photosensitive plastic to be irradiated. Whenthe illumination pattern exceeds, radially or laterally, a certaintolerance value that is determined beforehand for a time period that islikewise determined beforehand, the irradiation is interrupted and onlycontinues after the target state has been reached again. The duration ofthe irradiation is evaluated in order to ensure the respective dose andto match it to the desired preset values. The tolerance is selecteddepending on the required accuracy for reaching the reference state.

When tolerances that were determined beforehand are exceeded radially orlaterally, the illumination pattern can deliberately follow the eyemovement. This is advantageous in that the irradiation process need notbe interrupted. In order to steady the patient's eye, a luminousfixating mark can be projected on the eye. This light mark shouldadvantageously blink and should be presented to the patient opticallyfrom infinity in order to make it possible to see and recognize the markin a relaxed manner. In this connection, it is possible to project thefixating mark on the eye to be treated or on the other eye which is notto be treated. However, the fixating mark can also be used fordeliberate positioning of the patient's eye in certain directions. Forthis purpose, another microdisplay can advantageously be used in whichthe position of the mark can be shifted optoelectronically withoutmoving parts.

The tracking of the illumination pattern on the eye can likewise becarried out in an advantageous manner without any moving parts in thatthe pattern is simply displaced close in time on the optoelectroniccomponent corresponding to the scaled preset of the eyetracker unit.

The illumination for the camera of the eyetracker unit should be carriedout in a spectral range other than that of the observation wavelengthand treatment wavelength. This prevents reciprocal influencing of thebeam paths. The use of an eyetracker unit with IR illumination andcorresponding tracking of the pattern is especially advantageous whenparticularly finely structured illumination patterns are to be used forhigher aberration refraction correction.

For purposes of visual monitoring, it is possible to display the targetfield, tolerance field and tracking field in the observation unit. Thisis carried out by reflecting into the eyepiece or by imaging in a planeconjugate to the target object in which a corresponding display islocated.

Irradiation, e.g., for polymerization of artificial eye lenses, requiresillumination sources 2 having a high UV component such as mercury arclamps, xenon lamps or UHP lamps. However, because of this high UVcomponent of the light, particular attention must be paid to thepermissible radiation load corresponding to current guidelines, andsteps may have to be taken for specific attenuation of harmfulcomponents, e.g., by means of suitable edge filters. The irradiationunit which comprises the illumination source 2 and the optoelectroniccomponent 3 and which is constructed as an independent unit in thisexample can be used as an accessory unit for various ophthalmologicalinstruments such as slit lamps, fundus cameras, laser scanners and OPMIdevices in order to generate illumination structures or irradiationstructures with a defined dosage. However, the irradiation unit can alsobe used as an accessory unit or as an independent device for differentdermatological irradiation devices.

The solution according to the invention is chiefly provided forpost-operative fine adjustment of the refractive power of photosensitiveplastics already implanted in the eye. These photosensitive plastics canbe optical lenses as well as other optical elements which are placed inthe cornea in a specific manner and which cause a change in therefraction relationships of the cornea through their shape and position.

Since it is possible to adapt to individual result data, other fields ofapplication are opened up by the possibility of realizing dynamicprocesses and online regulation. For example, combined determination ofinitial data, i.e., of the refraction state, in the form of wavefrontanalyses and corneal topography is possible. During exposure, theeyetracker unit can be used for monitoring the position and for trackingthe pattern on the eye to improve the process of positioning or trackingthe illumination pattern also during long irradiation times of severalseconds. It is even possible to determine the refraction state onlineduring treatment depending on the achieved processing state of theobject to be illuminated.

By means of directed beam deflection within the lens or by means ofother optically active shaped parts, the image center or determinedpoints of the imaging could be deflected onto other areas of thereceiver. This is useful, for example, when the patient's retina isseverely damaged by scotomas in determined areas which can no longercontribute to visual perception. Through specific individual alterationof the local refractive power within the lens, the imaging can beshifted to healthy areas of the retina.

Further, application in photodynamic therapy is also possible. In thisway, progressive diseases of the macula which could not be haltedpreviously can now be stopped even in the visual center through a novellaser procedure by irradiation of a newly developed dye.

However, application for achieving dermatological results in whichdetermined effects can be produced by the introduction or addition oflight-sensitive materials and subsequent structured irradiation is alsoconceivable.

While the foregoing description and drawings represent the presentinvention, it will be obvious to those skilled in the art that variouschanges may be made therein without departing from the true spirit andscope of the present invention.

1. An arrangement for an illumination/irradiation of a human eye,particularly of photosensitive, optically active plastics implanted inthe eye, comprising: an illumination unit for illuminating the activeplastics; an optical imaging system responsive to the illumination unitfor imaging data on measured values of the active plastics; anevaluating unit responsive to the measured values; a central controlunit for acquiring and entering said data; and an output unit forvisualization and readout of said data; said illumination unit forgenerating an illumination which is variable with respect to time and/orspace.
 2. The arrangement for the illumination/irradiation of a humaneye according to claim 1, wherein the illumination unit comprises anillumination source and an optoelectronic component.
 3. The arrangementfor the illumination/irradiation of a human eye according to claim 2,wherein a microdisplay or a microscanner mirror is used as saidoptoelectronic component which is controllable with respect to lighttransmission, light reflection or light emission.
 4. The arrangement forthe illumination/irradiation of a human eye according to claim 1,wherein the central control unit is used for further processing andstoring said data and has a user surface and an interface.
 5. Thearrangement for the illumination/irradiation of a human eye according toclaim 1, wherein the evaluating unit comprises an image-recording andimage-processing unit.
 6. The arrangement for theillumination/irradiation of a human eye according to claim 1, wherein amonitor, a printer and/or a HMD (head mounted display) are used as saidoutput unit for the visualization and readout of said data.
 7. Thearrangement for the illumination/irradiation of a human eye according toclaim 1, wherein the optical imaging system has an adjustable numericalaperture and/or a variable back focus or focal length for sharp imagingof the illumination pattern in different planes.
 8. The arrangement forthe illumination/irradiation of a human eye according to claim 1,wherein a self-luminous array is used instead of the illumination unit.9. The arrangement for the illumination/irradiation of a human eyeaccording to claim 1, wherein an eyetracker unit is provided andcomprises a camera and a preferably infrared illumination which iscoupled in, for example, by means of a beam splitter.
 10. Thearrangement for the illumination/irradiation of a human eye according toclaim 1, wherein a fixating mark is additionally projected on the eye tobe treated or on the other eye which is not to be treated, this fixatingmark being formed as a blinking light mark which is presented opticallyfrom infinity and/or is adjustable to the refraction state of thepatient.
 11. The arrangement for the illumination/irradiation of a humaneye according to claim 1, wherein the arrangement is used for theillumination of photosensitive plastics already implanted in the eye, inparticular intercomeal rings.
 12. The arrangement for theillumination/irradiation of a human eye according to claim 1, wherein afixating/mark is additionally projected on the eye to be treated or onthe other eye which is not to be treated, this fixating mark beingformed as a blinking light mark which is presented optically frominfinity and is freely adjustable with respect to its attitude andposition.
 13. A device for the illumination/irradiation of a human eyeaccording to claim 1, wherein the illumination unit which comprises anillumination source and an optoelectronic component is constructed as anindependent unit which can be used as an accessory unit for variousophthalmological instruments comprising slit lamps, fundus cameras,laser scanners and OPMI devices in order to generate illuminationstructures or irradiation structures with a defined dosage.
 14. Thedevice for illumination/irradiation according to claim 1, wherein theillumination unit which comprises an illumination source and anoptoelectronic component is constructed as an independent unit which canbe used as an accessory unit for various dermatological irradiationinstruments in order to generate illumination structures or irradiationstructures with a defined dosage.
 15. A method for anillumination/irradiation of a human eye, particularly when operating anarrangement comprising an illumination unit for illuminating the eye, anoptical imaging system responsive to the illuminating unit for imagingdata on measured values of the eye, an evaluating unit responsive to themeasured values a central control unit for processing and storing data,and an output unit for visualization and readout of said data; themethod including the steps of generating an illumination by theillumination unit which is variable with respect to time and/or space,and applying said illumination to photosensitive, optically activeplastics implanted in the eye.
 16. The method for theillumination/irradiation of a human eye according to claim 15, furthercomprising the steps of entering the result data which have beendetermined beforehand manually or by transferring the data via anexisting interface or through a decision by the arrangement itself. 17.The method for the illumination/irradiation of a human eye according toclaim 15, including the step of imaging the irradiation patterngenerated by the illumination unit, comprising an illumination sourceand an optoelectronic component, by the imaging system in a freelyadjustable object plane.
 18. The method for the illumination/irradiationof a human eye according to claim 15, wherein an automatic imageevaluation and/or online control are/is made possible based on themeasured values determined by the evaluating unit.
 19. The method forthe illumination/irradiation of a human eye according to claim 15,including storing determined data for recording, documentation andevaluation.
 20. The method for the illumination/irradiation of a humaneye according to claim 15, wherein evaluation results are documented bythe output unit.
 21. The method for the illumination/irradiation of ahuman eye according to claim 15, wherein static or dynamic irradiationpatterns geared to a specific application can be generated for directedspatial and temporal sequences.
 22. The method for theillumination/irradiation of a human eye according to claim 15, whereinparameters which are required for an intended purpose are determined onthe basis of these data by the central control unit and conveyed to theillumination unit.
 23. The method for the illumination/irradiation of ahuman eye according to claim 15, wherein an eyetracker checks whether ornot generated illumination patterns strike exactly areas of the eye orof a photosensitive plastic to be irradiated during the irradiation. 24.The method for the illumination/irradiation of a human eye according toclaim 15, wherein generated illumination patterns track a possible eyemovement by an eyetracker unit and the illumination unit.
 25. The methodfor the illumination/irradiation of a human eye according to claim 15,wherein a generated illumination pattern is used for the illumination ofsaid photosensitive plastics already implanted in the eye, in particularintercorneal rings.